In a manufacturing process a machine produces bolts that have an average length of 3 inches with a variance of .03.If we randomly select three bolts from this process: What is the probability the mean length of the bolt is at most 3.1 inches?
A)84.13%
B)100 %
C)71.57 %
D)28.43 %
E)15.87 %

Question

Quizplus · Accepted Answer

The sampling distribution of the mean has a mean of 3 inches and a standard deviation of sqrt(0.03/3). Using the Z-score formula, the Z-score for 3.1 inches is (3.1-3)/(sqrt(0.03/3)) = 1. The probability of a Z-score less than or equal to 1 is approximately 0.8413 or 84.13%.

In a Manufacturing Process a Machine Produces Bolts That Have